Hydrostatic transmissions are widely used in a variety of applications such as earth moving machines, agricultural machines, and other industrial or domestic machines. Hydrostatic transmissions use a fluid such as hydraulic fluid to transmit power from a power source, e.g. an engine or an electric motor, to a driven mechanism, e.g. a wheel of a tractor, excavator or some other driven load. A typical hydrostatic transmission system includes a pump driven by a prime mover and a fluid-driven motor driven by the pump. In addition, such a system includes a reservoir that stores and provides fluid when required, e.g., charged oil to a hydraulic pump. Often, the prime mover, the fluid pump, fluid-driven motor, and reservoir are spaced from one another. To interconnect these parts, various additional components like connecting shafts, hoses, pipes, and/or fittings are used in a complicated manner. Moreover, these components are susceptible to damage or degradation, particularly in a harsh working environment, and thereby can cause increased machine downtime and reduce reliability of the machine.
To control the flow in the system, the fluid pump can be a variable-displacement pump, e.g., a variable-displacement hydraulic pump, and/or a directional flow control valve (or another type of flow control device) can be included in the system. For example, in conventional hydraulic systems, an electric motor that drives the operation of a hydraulic pump is often run at constant speed and a directional flow control valve, for example, can provide the appropriate porting to the hydrostatic transmission to control the speed and direction of the fluid-driven motor in the hydrostatic transmission. Typically, the electric motor and hydraulic pump are run at a high speed, which builds up temperature in the hydraulic fluid. Thus, the reservoir also acts to keep the average fluid temperature down by increasing the fluid volume in the system. However, these hydraulic systems can be relatively large and complex. In addition, the various components are often located spaced apart from one another. To interconnect these parts, various additional components like connecting shafts, hoses, pipes, and/or fittings are used in a complicated manner. Moreover, these components are susceptible to damage or degradation in harsh working environments, thereby causing increased machine downtime and reduced reliability of the machine.
Further limitation and disadvantages of conventional, traditional, and proposed approaches will become apparent to one skilled in the art, through comparison of such approaches with embodiments of the present invention as set forth in the remainder of the present disclosure with reference to the drawings.